Jumping Islands in pockets

[John Q]

I am machining a mold cavity with islands in it.

It is 17 inches deep and the islands are 16 inches

tall. I used the surface pocket routine with depths. My problem is there is not enough z travel on the cnc machine and I am having to used 3 different tools one longer than the other. The first tool works great for the first depth. The second one cuts good but it tries to jump the islands and the second tool is to long. There is not enough z travel on the machine to jump the islands. How can you make the tool stay down and just cut around the islands and not jump them using the surface poscket routine. Thank You!!!!!

[cadist]

IMHO You can adjust your clearance and retract value to incremental.

Though very dangerous but a little care should sort it out.

PS Dont forget to disable the auto-toolchanger.

[John Q]

I am not sure I explained myself well.

I am using 3 surface pocket routines with

three different tools If that helps.

I have tried to change the clearance and retract

heights but it still jumps the islands when it machines. I was told be someone to change gap

size to 20 and that would work but it did not change anything.

[cadist]

John can you put your file on ftp. for others to have a look.

Also is it possible to divide your pocket with containment boudaries.

[John Q]

Yes I will I will call it Johnisland

[John Q]

It is on there now under the mc9 folder

Thanks for your time

[Teh Bear without Brains kinda idiot]

My settings were :

True spiral pocket type spiral inside to outside ,unselected prompt for entry point ,

gap settings motion -smooth ,optimize cut order on and it looks nice on verify but you can scrap part anyway ,cause you have G0 movements under part and nor backplot nor verify can show you the real movement cause it`s machine specific.

Change all your Go x y movements to g1

or what I would do :

split your part to separate pockets and mill them ,100 % safe

 

HTH

[John Q]

It looks good in verify but if you

look at it in the front view of backplot

you can see it is still jumping up to the

top of the islands and the tool is too long

for that. Thank for the information!

I am in trouble on this thing so I appreciate

any advice you can give me!

[Teh Bear without Brains kinda idiot]

I say make check boundaries and mill your pocket as a set of separate pockets ,stay away from moving not over Islands even if verify and backplot is OK ,you can scrap your part .

Do`nt be obstinate ,go simple ,safe ways !

[John Q]

I understand how to make check surfaces and I understand how to create geometry at the different levels I want to machine. But I am not sure what you mean by check boundries.

I did split the surfaces up at different levels and tried that but it still jumped up and cut off the top of the islands. I am almost there thanks

[Teh Bear without Brains kinda idiot]

from mc help

---

A tool containment boundary is a closed chain of curves that defines and limits the machining area in an operation. Using a tool containment boundary ensures that the tool stays within the specified area. A tool containment boundary is usually geometry created specifically for that purpose. The graphics below show an example of a tool containment boundary (isometric view) where the boundary is purple and located slightly above the surface. The tool containment boundary can be at any Z depth relative to the part.

 

---

[Hardmill]

I would think you could control it w/ cut depths.

Set your min depth for that tool to just below the

top of the islands. It should only cut whats below.

Be careful Safety first

 

 

PEACE

[John Q]

Hey guys Thanks

I did try boundary I have used them before but not to control z depths it made the tool stay within that boundary in x and y but it still jumps the islands in z. Maybe I needed 2 boundaries at 2 depths? Also if you look at the file I tried cut depths, that controlled how deep it cut per surface pocket routine but it still jumps the islands. I also tried gap settings

[Teh Bear without Brains kinda idiot]

You do not understand

split your boundaries to separate pockets and copy your program needed number of times and select different boundaries every time so that a tool will not have inside islands and you can so set it jump under the part .

HTH